Well, I don't know just how cold Hong Kong is : but you must dress very warmly. More warmly than you would if you werent going to fly. The trick is to keep the blood flowing to your fingers. If you don't, your hands become numb. So dress extra warm. And there are small chemical pouches available in sporting good stores that produce heat. You can keep them in you pockets or in your gloves when you are not flying. And a thremos of hot fluids to drink. When your hands go numb, you are out of business.

In cold temperatures, it may be neccessary to prime the engine through the exhaust port. At least the first time you start the engine. When you land, cover the engine with a rag or something to keep it warm.